The Allen-Bradley 1785-L40E is a Programmable Logic Controller (PLC). This controller module is ideally used for medium to large application and capable of interfacing simultaneously with a variety of devices for automation of machine s or processes. The 1785-L40E is installed to a 1771 chassis. This chassis hosts the electronic backplane where system power is supplied and distributed among other modules including the 1785-L40E controller. Compatible chassis for this controller are 1771-A1B, 1771-A2B, 1771-A3B, 1771-A3B1, and 1771-A4B while compatible power supplies are 1771-P4S, -P6S, -P4S1, -P6S1. The controller’s current draw is 3.3A with power dissipation of 17.3W.

The 1785-L40E supports a variety of industrial protocols via the embedded communication ports such as Two (2) Data Highway + (DH+) /Remote I/O (RIO) (Adapter or Scanner) combination port, One (1) serial port, that supports RS-232, 423 and RS-422A EIA standards and One (1) Ethernet communication port that supports 10/100 Mbps transmission speed. All these communication ports may be used for communicating with visualization system, PLC5 controllers and other Allen-Bradley controllers, and other devices.

This controller supports a variety of programming languages per IEC 61131-3 standard. Supported programming languages include Sequential Function Chart (SFC), Ladder Logic, and Structured Text (ST).

The 1785-L40E supports implementation of automatic and manual control of discrete and analog devices, perform signal conditioning, implementation of advanced control algorithms such as Proportional-Integral and Derivative (PID) functions, among other industrial functions. This controller has built-in memory of 48KB can handle 2048 any mix or 2048 input and 2048 output (complement.) It can support up to 61 chassis wherein 1 chassis is the local chassis and the other 60 chassis can be remote I/O systems.

This module is pre-installed with an Allen-Bradley 1770-XYC battery module. It supports installation of optional backup memory devices such as 1785-ME64, 1785-ME32, or the 1785-M100 lithium batteries. The 1785-L40E is compatible with 8-point, 16-point, 32-point, and 1771 intelligent I/O modules, and the controller offers users a maximum selectable I/O scan time of just 0.5ms for the extended-local I/O adapter, an I/O scan time of 10 milliseconds for the remote I/O rack at 57.6 kbps, and a scan time of 3 milliseconds for the remote I/O rack at 230.4 kbps. It supports maximum of 16 I/O racks (0 to 15), and up to 61 I/O chassis links. The 1785-L40E addresses the I/O hardware via 3 different modes. Specifically, these addressing methods are 2-slot mode which addresses any mix of 8-point modules and a pair of 16-point modules, the 1-slot mode which addresses any mix of 8 and 16-point modules, and 1 pair of 32-point I/O modules, and the half-slot mode which addresses any mix of 8-point, 16-point, and 32-point modules. The 1785-L40E has 1 dedicated 15-pin, Ethernet/IP port (with TCP/IP protocol), 2 Data Highway Plus (DH+)/Remote I/O (Adaptor or Scan) ports for connection to the Allen-Bradley Data Highway (DH+) network, and 1 RS-232-C, 422-A, and 423-A serial communication port. The controller has an internal circuit clock that has a +/- 5 min per month of accuracy variation, and it will function without de-rating at a temperature of 0 to 60 degrees Celsius (32 to 140 degrees Fahrenheit) around 5 to 95% non-condensing humidity range. The controller has an operational shock withstand of 30G with 1G operational vibration at 10 to 500 Hertz without, and is CSA, C-TICK, CE, and UL-certified. It weighs averagely 1.38 kilograms (3.0 pounds) and comes in an open enclosure.